Biomechanical Study of PEEK Condyle Prosthesis Printed by Fused Deposition Modeling and Selective Laser Sintering / 医用生物力学

Objective To make finite element analysis and compressive performance test on three-dimensional (3D) printed personalized poly-ether-ether-ketone (PEEK) condyle prosthesis, so as to analyze stress distribution characteristics and mechanical properties of the prosthesis, and to evaluate its clinical value and prospect. Methods The finite element models of PEEK condyle prosthesis, mandible and fixation screw were established by software such as CBCT, Mimics, Geomagic Studio, SolidWorks and ANSYS Workbench. The maximum mastication force was applied, and the maximum stress of the condyle prosthesis and screw, as well as the stress and strain of the mandible were recorded. In order to simulate the actual clinical situation, a special fixture was designed to test compression performance of the condyle prosthesis prepared by the fused deposition modeling (FDM) and selective laser sintering (SLS) at the rate of 1 mm/min. Results The peak stress of the PEEK condyle prosthesis was 10.733 MPa, which was located at the back of the condyle neck. The peak stress of 5 fixing screws was 9.707 5 MPa, which appeared on the 2# and 5# screws near the trailing edge of the mandibular ascending branch. The peak stress of both the prosthesis and the screw was smaller than its yield strength. The maximum pressure of the condyle prosthesis prepared by FDM and SLS was (3 814.7±442.6) N and (1 193.970±260.350) N, respectively. Compared with the SLS preparation, the FDM prepared prosthesis not only had higher compression strength but also better toughness. Conclusions The 3D printed personalized PEEK condyle prosthesis shows uniform stress distributions and good mechanical properties, which can provide the theoretical basis for PEEK as reconstruction material for repairing temporomandibular joint.

Application and prospects of 3d printing technology in dental manufacturing / 中国组织工程研究

BACKGROUND: In the case of tooth defect or missing, the treatment should be achieved by making a personalized prosthesis. Traditional manufacturing process is time-consuming, costly and accurate. After the introduction of 3D printing technology into dental manufacture, the manufacturing efficiency and quality can be improved to a certain extent. OBJECTIVE: To introduce the application of 3D printing technology in dental manufacture, discuss the bottleneck in recent application, and guide the development of 3D printing technology in dental manufacture. METHODS: The authors used the search times "3D printing, metal implant, dental manufacturing, dental restorations” to search Web of Science, Wanfang, CNKI databases in English and Chinese separately to search papers published during 1980-2019. 261 papers were preliminarily retrieved and 60 of them were included in the final analysis. RESULTS AND CONCLUSION: 3D printing dental mold, digital implant guide plate and wax pattern have been widely used in dental manufacture. 3D printing technology has been widely used in dental manufacture. The most widely used six processes are stereo lithography appearance, laminated object manufacturing, fused deposition modeling, selective laser sintering, selective laser melting, and inkjet printing. There are some technical bottlenecks in the application of 3D printing technology in the field of dental manufacturing. After breaking through technology bottlenecks, 3D printing will be more useful in the field of dental manufacturing in the future.

Research status of 3D⁃printed composite PVA bone tissue engineering scaffolds / 口腔疾病防治

@# Three dimensionally printed composite porous bone tissue engineering scaffolds have become a research focus. Composite polyvinyl alcohol (PVA) has good biocompatibilityand degradability, but it cannot be prepared indepen⁃dently because it cannot resist highmechanical resistance. This material shows many advantages, such as good biocom⁃patibility, degradability and mechanical properties, when compounded with other materials with good mechanical proper⁃ties and good biocompatibility. Therefore, 3D printed composite PVA scaffold material can optimize the performance of PVA scaffolds. This article reviews 3D printing bone scaffold technology, polyvinyl alcohol (PVA), and composite PVA scaffolds for in vivo and in vitro bone formation.

Application of 3D printing technology in preparation of scaffolds for periodontal tissue regeneration / 口腔疾病防治

@#How to obtain ideal regeneration of periodontal tissue remains a challenge in the clinical treatment of periodontitis. Three-dimensional printing technology is based on computer-aided design, which produces materials with specific 3D shapes by layer-by-layer superposition, and has been applied to periodontal tissue regeneration therapy, this method offers hope to achieve ideal periodontal regeneration. This article reviews the application of 3D printing technology in the field of periodontal tissue regeneration. The literature review results show that 3D printing technology can design three-dimensional structures using computer software in advance and produce materials with specific three-dimensional structures. 3D printing technology mainly includes selective laser sintering, selective laser melting, extrusion forming printing and 3D bioprinting. At present, the support materials prepared by 3D printing technology include ceramic materials, polymer materials and metals. Submaterials have been extensively studied given their high adjustability, and 3D-printed personalized titanium mesh has been applied in the clinic. Multiphase materials prepared by 3D-printing technology can regenerate periodontal tissue in animal experiments, but the effect is not good in patients with periodontitis. In addition, 3D printing of composite scaffolds for periodontal tissue regeneration need to be further studied.

Selective laser sintering and performances of porous titanium implants / 华西口腔医学杂志

OBJECTIVE@#This work aims to analyze the mechanical properties and biocompatibility of porous titanium (Ti) implants fabricated by selective laser sintering (SLS) and investigate the promotion of osseointegration by porous titanium implant combined with chitosan (CS)/hydroxyapatite(HA) composite coating.@*METHODS@#Ti6Al4V specimens were prepared, and CS/HA composite coating was fabricated on the surface of a portion of the specimens. The mechanical properties of the samples were observed by scanning electron microscope. MC3T3-E1 cells were cultured in vitro, and their biological properties in vitro were analyzed using live and dead viability cell staining method, methyl thiazolyl tetrazolium (MTT) staining, and alkaline phosphatase (ALP) level detection. The thread implant specimens were implanted in the femoral condyle of rabbits, and biological performance was evaluated in vivo.@*RESULTS@#Quasi-elastic gradient of porous specimens decreased with increasing porosity, and the quasi-elastic gradient were close to cortical and cancellous bone when the porosities were 30% and 70%. The specimens showed good biocompatibility. Combined with CS/HA coating, the implants promoted the proliferation and differentiation of MC3T3-E1 cells and facilitated the entry of bone tissue into pores and good osteogenesis.@*CONCLUSIONS@#The porous titanium implant exhibited favorable mechanical properties and biocompatibility. Combined with CS/HA coating, the implant exhibited bone inducibility, which leads to stable osteogenesis.

Solid Freeform Techniques Application in Bone Tissue Engineering for Scaffold Fabrication

Solid freeform techniques are revolutionising technology with great potential to fabricate highly organized biodegradable scaffolds for damaged tissues and organs. Scaffolds fabricated via Solid freeform (SFF) techniques have more pronounced effect in bone tissue engineering. SFF techniques produce various types of scaffolds from different biomaterials with specific pore size, geometries, orientation, interconnectivity and anatomical shapes. Scaffolds needs to be designed from such biomaterials which can attach directly to natural tissues and mimic its properties, so ideally mechanical properties of scaffolds should be same as that of regenerating tissues for best results. The scaffolds designed without optimized mechanical properties would lead to the reduced nutrition diffusion within tissue engineered constructs (TECs) causing tissue necrosis. These scaffolds are mainly processed from ceramics and polymers like calcium phosphate, polydioxane, €-polycaprolactone, polylactic and polyglycolic acids etc. While, hydrogel scaffolds provide bridge for encapsulated cells and tissues to integrate with natural ECM. Likewise, 2D images from radiography were not sufficient for the prediction of the brain structure, cranial nerves, vessel and architecture of base of the skull and bones, which became possible using the 3D prototyping technologies. Any misrepresentation can lead to fatal outcomes. Biomodelling from these techniques for spinal surgery and preoperative planning are making its way toward successful treatment of several spinal deformities and spinal tumor. In this review we explored laser based and printing SFF techniques following its methodologies, principles and most recent areas of application with its achievements and possible challenges faced during its applications.

In vitro evaluation of the bond strength between various ceramics and cobalt-chromium alloy fabricated by selective laser sintering

PURPOSE: This study aimed to present the clinical applicability of restorations fabricated by a new method, by comparing the bond strength of between ceramic powder with different coefficient of thermal expansion and alloys fabricated by Selective laser sintering (SLS). MATERIALS AND METHODS: Fifty Co-Cr alloy specimens (25.0 x 3.0 x 0.5 mm) were prepared by SLS and fired with the ceramic (8.0 x 3.0 x 0.5 mm) (ISO 9693:1999). For comparison, ceramics with different coefficient of thermal expansion were used. The bond strength was measured by three-point bending testing and surfaces were observed with FE-SEM. Results were analyzed with a one-way ANOVA (alpha=.05). RESULTS: The mean values of Duceram Kiss (61.18 +/- 6.86 MPa), Vita VM13 (60.30 +/- 7.14 MPa), Ceramco 3 (58.87 +/- 5.33 MPa), Noritake EX-3 (55.86 +/- 7.53 MPa), and Vintage MP (55.15 +/- 7.53 MPa) were found. No significant difference was observed between the bond strengths of the various metal-ceramics. The surfaces of the specimens possessed minute gaps between the additive manufactured layers. CONCLUSION: All the five powders have bond strengths higher than the required 25 MPa minimum (ISO 9693); therefore, various powders can be applied to metal structures fabricated by SLS.

Fabricating a Ceramic-Pressed-to-Metal Restoration with Computer-Aided Design, Computer-Aided Manufacturing and Selective Laser Sintering: A Case Report

Even though a conventional metal ceramic restoration is widely in use, its laboratory procedure is still technique-sensitive, complex, and time-consuming. A ceramic-pressed-to-metal restoration (PTM) can be a reliable alternative. However, simplified laboratory procedure for a PTM is still necessary. The article is to propose a technique that reduces time and effort to fabricate a PTM with the aid of computer-aided design, computer-aided manufacturing and selective laser sintering technologies.

Bond and fracture strength of metal-ceramic restorations formed by selective laser sintering

PURPOSE: The purpose of this study was to compare the fracture strength of the metal and the bond strength in metal-ceramic restorations produced by selective laser sintering (SLS) and by conventional casting (CAST). MATERIALS AND METHODS: Non-precious alloy (StarLoy C, DeguDent, Hanau, Germany) was used in CAST group and metal powder (SP2, EOS GmbH, Munich, Germany) in SLS group. Metal specimens in the form of sheets (25.0 x 3.0 x 0.5 mm) were produced in accordance with ISO 9693:1999 standards (n=30). To measure the bond strength, ceramic was fired on a metal specimen and then three-point bending test was performed. In addition, the metal fracture strength was measured by continuing the application of the load. The values were statistically analyzed by performing independent t-tests (alpha=0.05). RESULTS: The mean bond strength of the SLS group (50.60 MPa) was higher than that of the CAST group (46.29 MPa), but there was no statistically significant difference. The metal fracture strength of the SLS group (1087.2 MPa) was lower than that of the CAST group (2399.1 MPa), and this difference was statistically significant. CONCLUSION: In conclusion the balling phenomenon and the gap formation of the SLS process may increase the metal-ceramic bond strength.

Preparation and clinical application of a nose prosthesis by means of selective laser simtering and wax powder / 中华医学美学美容杂志

Objective To explore the clinical application of reconstructing silicone elastomer nose prosthesis by means of selected laser sintering and wax powder PCPI. Methods Laser scanning was used to get the 3-D data of a nose model. Surfacere 10.0 etc softwares was used to reconstruct the nose by mirroring the digitalized model of absent nose. Selective laser sintering and wax powder was chosen to fabricate a wax nose model and the nose prosthesis made by silicone clastomer. Results Perfect silicone clastomer nose prosthesis was made for 2 patients. Conclusion This study suggests that the wax nose model and the new wax powder can meet the requirement of clinical expectation for maxillofacial prosthesis.

Evaluation of a dental wax formed by laser sintering technology / 实用口腔医学杂志

Objective:To evaluate a new wax formed by laser sintering technology(SW-1)for dental use.Methods:The melting point,hardness and viscosity of SW-1,normal dental modeling wax and LongYuan's wax formed by laser sintering were tested and compared.Linear shrinkage,plastic deformation and toughness of SW-1 were estimated by national standards.Results:There were no significant differences between SW-1and the normal dental modeling wax in the properties of melting point 〔(61.1?1.63)℃,(61.7?1.96)℃〕and hardness 〔(75.2?0.62)HA,(74.0?0.54)HA〕;but when compared with melting point(78.3?1.07)℃and hardness(94.0?0.38)HA of LongYuan's wax formed by laser Sintering,those of SW-1 were significantly different.Viscosity of SW-1(2 016?136.9)MPa?s showed significant difference when compared with that of normal dental modeling wax(9.06?0.258)MPa?s and LongYuan's wax formed by laser Sintering(2 876?81.7)MPa?s.Linear shrinkage of SW-1(0.2%)met the national standards,while plastic deformation(10%,43 ℃)and toughness(broken when bent,20 ℃)of SW-1 did not meet such standards.Conclusion:SW-1 may be the proper laser sintering material for dental use,and has a good prospect in future.

Fabrication of a nose prosthesis by means of selective laser sintering and wax powder / 实用口腔医学杂志

Objective:To reconstruct a 3-D wax nose model and make a s ilicone elastomer nose prosthesis. Methods:Laser scanning was us ed to get the data of a nose model, selective laser sintering and wax powder wer e used to fabricate a wax nose model,the nose prosthesis was made by silicone el astomer. The differences in length(L),width(W),deepth(D),height(H) and tip-angl e(TA) among the nose models made with plaster, wax powder and silicone elastomer were compared. Results:L(mm) in plaster, wax and silicon e models was 36.61,36.60 and 36.60 respectively.W(mm),D(mm),H(mm) and TA(?) in the three kinds of models were the same:36.23,18.45,43.14 and 74.57 respectively .Conclusion:Nose model made of the wax powder is precise and can meet the requirements for maxillofacial prosthesis.